ANALYTICAL STUDIES OF HV INSULATORS IN SAUDI-ARABIA - THEORETICAL ASPECTS

Digital computer studies of long contaminated insulator strings have b een carried out using linear, lumped circuit models. These studies enh ance the evaluation of voltage distribution, currents, phase angle and wattage for each unit on the string for practical combinations of uni form and nonuniform distribution of contamination. The variations in p erformance as a function of numerous, stray capacitance and shielding fields are carried out for a wide range of pollution index, tower desi gn varying at different areas, and conditions of Saudi Arabia. The stu dies are extended to the physics of the evaluation of the voltage dist ribution and phase angle variations along the insulator string as the surface is changed from clean, to dirty, to contaminated, to polluted. The iteration technique is used to explore the effect of nonlineariti es in resistance as a function of temperature variations and current l imits. Changes in surface resistance due to the liberated energy, whic h dries the contamination or arrests the accumulation of moisture upon the insulation surface, are considered in these studies. Studies are carried out on a per-unit basis to simplify the adoption of the result s to insulator strings used at different voltage levels, under any deg ree of uniform or nonuniform distribution of contaminants along the in sulator string.